A turnover model for carbon reactivity I. Development

Recent studies of the carbon-oxygen reaction have increasingly identified the importance of the role of surface complexes in the reaction mechanism. The observation that the complexes can be characterized by their activation energy for thermal decomposition (which ties in the range 160-420 kJ mol-1) provides the basis for a stochastic description of the behavior of these complexes and their processes of formation and gasification. From independent studies of the kinetics of complex formation (R1b), of thermal decomposition (R2), and of reaction with oxygen (R3), an overall model for the oxidation of carbon has been developed. C(_) + O(2) -->.... C(O) + CO (R1b) C(O) .... --> C(_) + CO,CO(2) (R2) C(O) + O(2) --> C(O) + CO CO(2) (R3) The broad range of types of complex, characterized by their activation energies for thermal decomposition gives rise to a wide diversity of behavior under any given reaction conditions. The combination of these provides a very accurate model of the observed reaction rate of a model carbon. (C) 2001 by The Combustion Institute.